Precise determination of tooth root canal length and the diameter of the apical aperture is vitally important for correct endodontic cleaning and filling. The root canal must be precisely reamed and the pulp tissue completely removed because leaving some of the pulp tissue may lead to abscess. Removing more of the root canal structure than necessary is not desired and leaving pulp tissue within the canal is to be avoided. The dentist must know precisely the location and diameter of the apical aperture of the root canal in order to render the most effective and painless treatment.
The difficulty with completely cleaning the root canal is that the canal tapers to a narrow neck at the root apex and then widens again as it approaches the site of exiting from the root. This has been described as a funnel shape or even as the shape of a morning glory flower. The dentist must be aware of the probable canal configuration present and any common variants that might be present, the estimated length of the root(s), the site of exiting of the canal(s), and the estimated width of the canal(s). This is done by analyzing the preoperative radiographs available.
It has been clinically established that the root canal must be cleaned as thoroughly as possible to remove any remaining pulpal tissues, bacteria, toxins and debris. If the cleaning instruments or irrigating solutions are thrust through the apical foramen, tissues surrounding the tooth root may become inflamed or infected, leading to intense pain which may require surgery. Therefore, it is critical that the dentist know precisely the location and diameter of the apical foramen.